One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,11)(8,12)(9,10)(13,14,18,20)(15,23,25,16)(17,21,19,22)(24,27,26,28)(6,10)(11,12)(13,15)(14,16)(17,26)(18,25)(19,24)(20,23)(21,27)(22,28) involution — undirected(1,2,3,4)(5,7,9,8)(6,11,10,12)(14,20)(15,24)(16,27)(17,19)(23,28)(25,26)(5,8,9,7)(6,12,10,11)(13,16)(14,15)(17,27)(18,23)(19,28)(20,25)(21,26)(22,24)(13,17)(14,21)(18,19)(20,22)(24,26)(27,28) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.